3-D CT has the advantage to analyze the complex anatomical structures of the facial bones three-dimensionally compared with conventional radiograph. Observation and the measurement of 3-D image in any directions and inner structures of maxillofacial bones using cutting functions are possible on CRT.STL model (plastic actual model) reconstructed from CT images makes 3-D analysis of the facial bones easier. The aims of this study is to compare 3-D CT images and STL model in measurement accuracy and apply the measurement on STL model in the clinical cases to analyze the influence of mandibular deformity to the surrounding anatomical structure in the cranio-facial region. 3-D CT images and STL models were made in a dry skull and measurement accuracy was compared, Furthermore we applied 3-D CT and plastic models in three clinical cases (Coronoid process hyperplasia 2 cases, TMJ ankylosis 1 case) Our results showed the measurement accuracy on the plastic model was notably superior to that of
… More the 3-D images on CRT.The difference in measurement accuracy might be due to the difficulty determining The measurement points in the 3-D images on CRT.3-D analysis on STL model was more easier than the ordinal 2-D analysis (cephalometry analysis) and made it possible to measure the points which is not possible on 2-D cephalometry. The specific gravity of the monomer of the pjastic material (Desolite SCR 301. Japan Gum Co. Ltd.) was 1.08 Dm and 1.15 Dp in resin. Volume shrinking was a -6.09% and -2.03% in linear shrinking by polyimerisation. ln clinical cases, plastic models made it possible to (10 close observation of the complex anatomical relationship which are easily overlooked on axial CT images and even on 3-D CT images. The plastic model duplicated the exostosis of the inner surface of the malar bone facing the concavity of the elongated process suggesting the direct functional cause of the patient's trismus. The fact that the coronoid process has been elongated in the case with TMJ ankylosis suggests that elongation could occur by the existed neighbouring bone deformity causing trismus lead to the muscle tension. It is thought that even in less extreme cases of coronoid process hyperplasia the processes can come into contact with the malar bones, thus causing trismus when the craniofacial deformity has existed.従って既存の周囲顎顔面頭蓋の変形により筋突起の長さが著明でなくとも頬骨に早期接触し、開口障害を引き起こす可能性も考えられた。 Less